Ends down monitoring

ABSTRACT

A pneumatic device, particularly for detecting an ends down condition on a spinning frame, having a piston member with a passageway connecting its rear to an enclosed region at its front and movable in a bore of a housing rearward against a spring when a low pressure signal is applied to the device and communicated to the enclosed region via the passageway. In one embodiment, the piston member grips a movable electrode in its rear position and, as it returns forward after the signal is removed, drags the electrode forward against a spring to connect it to a stationary electrode and produce an electrical pulse and further generates pneumatic pulses by its forward and rear movements. In another embodiment, a valve stem blocks a passageway venting a chamber to the atmosphere when the end is up so that pressure is communicated to the region at the front of the piston member which moves rearward away from a transparent bezel and when the end is down the chamber is vented and the piston member moves forward until the colored front of the piston member is visible through the bezel. In yet another embodiment, the yarn itself blocks the passageway. In another embodiment, the ends down detector includes a pivotable member which engages the yarn at one end and has a magnet mounted on its other end so that when the yarn comes down the magnet moves adjacent a reed switch which is closed thereby. In one system a number of such reed switches are each connected to a unique combination of data lines and a recorder for each switch is likewise connected to the lines. The recorder has a normally closed relay connected to those lines to which the associated switch is not connected and a normally open relay connected to those lines to which the associated switch is connected so that a current path is completed through a recorder relay via all of the relay switches only when the associated reed switch is closed. In another system, a number of pneumatic devices are connected to a common manifold so that a pneumatic signal travels both directions in the manifold toward devices for detecting the arrival of the signal. The time interval between the arrival of the signal at the first device and the arrival at the second indicates the position of the pneumatic device producing the signal and accordingly the particular device producing the signal. In one embodiment, the arrival of the signal at the first device causes a wheel to begin rotating and sequentially connecting to a number of fixed contacts. The arrival of the signal at the second device causes an electrical signal to be coupled to the fixed contact to which the wheel is connected at that time. In a second embodiment, the arrival of the signal at the first device causes a pneumatic logic to sequentially move through a number of stages so that the stage activated at the time of arrival at the second device indicates the pneumatic device which produced the signal.

United States Patent [191 Joy [ ENDS DOWN MONITORING [75] Inventor:Raymond D. Joy, Clarksville, Va.

[73] Assignee: Burlington Industries, Inc.,

Greensboro, NC.

[22] Filedi July 9, 1970 [21] Appl. No.: 53,624

Primary Examiner-Louis R. Prince Attorney-Cushman, Darby and Cushman[57] ABSTRACT A pneumatic device, particularly for detecting an endsdown condition on a spinning frame, having a piston member with apassageway connecting its rear to an enclosed region at its front andmovable in a bore of a housing rearward against a spring when a lowpressure signal is applied to the device and communicated to theenclosed region via the passageway. In one embodiment, the piston membergrips a movable electrode in its rear position and, as it returnsforward after the signal is removed, drags the electrode forward againsta spring to connect it to a stationary electrode and produce anelectrical pulse and further generates pneumatic pulses by its forwardand rear movements. In another embodiment, a valve stem blocks apassageway venting a chamber to the atmosphere Oct. 9, 1973 when the endis up so that pressure is communicated to the region at the front of thepiston member which moves rearward away from a transparent bezel andwhen the end is down the chamber is vented and the piston member movesforward until the colored front of the piston member is visible throughthe bezel. In yet another embodiment, the yarn itself blocks thepassageway. In another embodiment, the ends down detector includes apivotable member which engages the yarn at one end and has a magnetmounted on its other end so that when the yarn comes down the magnetmoves adjacent a reed switch which is closed thereby. In one system anumber of such reed switches are each connected to a unique combinationof data lines and a recorder for each switch is likewise connected tothe lines. The recorder has a normally closed relay connected to thoselines to which the associated switch is not connected and a normallyopen relay connected to those lines to which the associated switch isconnected so that a current path is completed through a recorder relayvia all of the relay switches only when the associated reed switch isclosed. In another system, a number of pneumatic devices are connectedto a common manifold so that a pneumatic signal travels both directionsin the manifold toward devices for detecting the arrival of the signal.The time interval between the arrival of the signal at the first deviceand the arrival at the second indicates the position of the pneumaticdevice producing the signal and accordingly the particular deviceproducing the signal. In one embodiment, the arrival of the signal atthe first device causes a wheel to begin rotating and sequentiallyconnecting to a number of fixed contacts. The arrival of the signal atthe second device causes an electrical signal to be coupled to the fixedcontact to which the wheel is connected at that time. In a secondembodiment, the arrival of the signal at the first device causes apneumatic logic to sequentially move through a number of stages so thatthe stage activated at the time of arrival at the second deviceindicates the pneumatic device which produced the signal.

12 Claims, 23 Drawing Figures [451 Oct.9,1973

United States Patent [191 Joy EH I F 4 m m Z\ MW Q RU m 80 a? car:

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INVENTOR %"9.? 1. P9 y/va/wfl rfo y y, fig /WZMM ATTORNEYS PATENTEDUBT919?? 3,163,702

saw our n' INVENTOR 7Z9 /va/vaD. (/5 Y ATTORNEYS WGQWQ PATENTEI] OCT 9I973 SHEH war 11 INVENTOR Fm Mmwfl (/5 y J 9mm H 4 ATTORNEYS 1 ENDS DOWNMONITORING BRIEF DESCRIPTION OF THE PRIOR ART AND SUMMARY OF THEINVENTION The invention relates to a low pressure operated pneumatic andelectric pulsing device and to an ends down detecting and surveillermonitoring system.

Since fluidic devices which operate on the Coanda principle or Wallattachment effect devices which produce an output signal at very lowpressure have become popular, the need for relatively simple devicesthat can be operated by such low pressure signals to obtain pneumaticand/or electrical pulse signals of relatively short duration in order tosense signal or register a sequence of events which may occur inrelatively rapid successions has been evident.

The invention of this application as described below relates to such asimple fluidic device which incorporates a piston like member whichoperates against a low compression spring causing it to traverse intothe bore of a housing to produce a pneumatic output signal of shortduration, but sufficient intensity to operate an auxiliary devicemomentarily thus producing a pneumatic pulse. The device can beconnected to produce a vacuum pulse momentarily as the piston member isreleased and moves in response to the forces generated by its compressedspring out of the bore. By attaching clipper springs or a magnet to therear of the piston member, an electric switch can be implemented toproduce a momentary contact and electrical signal upon removing the lowpressure signal from the front of the piston, allowing the compressedspring to force the piston out of its bore and against the forward stop.

Such a device as described in detail below has a particular utility inthe environment of a textile mill and particularly for detecting andmonitoring an ends down condition on a spinning frame. Heretofore, ithas been difficult to detect, flag, register, totalize or signal when anend of yarn or the' like comes down on a spinning frame. One of theparticular problems is that the detecting mechanism must necessarily bevery sensitive and hence delicate in order to detect the end.Frequently, doffing or putting up an end destroys or insensitizesexisting detectors and further the oily, humid and dirty atmosphere inwhich the detecting and signalling devices operate frequently renderthem useless after a short operating interval.

Accordingly, it has been discovered that the fluidic mechanism such asdescribed above and in detail below is particularly suitable for sensingthe presence of an end or thread of yarn being run or wound at a veryhigh speed through the detecting device and producing a suitable signalfor triggering auxiliary devices to spot the position of the end that isdown and to also generate or close a switch or by some other means applyinformation to data collecting devices for further recording andreference.

Further, a system is described in detail below whereby a number of suchpenumatic devices which produce a signal in response to the detection ofan ends down condition are connected to a common manifold having devicesfor detecting the arrival of the signal thus produced mounted at both ofits ends. The time interval between the arrival of signal at the firstdevice and the arrival of the signal at the second device indicates theposition of the pneumatic ends down detector on the manifold, andaccordingly indicates which detector is producing the signal at the twodevices.

In one embodiment, the arrival of the signal at the first device causesa wheel to begin rotating and sequentially connect a contact mounted forrotation with the wheel to each of a plurality of fixed contacts. Thearrival of the signal at the second device causes an electrical signalto be coupled to the fixed contact to which the wheel is connected atthat time so that an electrical signal is passed to a recorder which isassociated with the pneumatic device producing the signal. In a secondembodiment, the arrival of the signal at the first device triggers apneumatic oscillator which thereafter shifts between a first and secondcondition, each shift causing a different stage and the recorderassociated with that stages to be activated. The stage which isactivated when the signal arrives at the second device is the stageassociated with the pneumatic device producing the signal, andaccordingly the recorder thus operated records which of the pneumaticdevices connected in common to the manifold produced the signal.

In a further embodiment, the detector comprises a pivotable member whichengages the yarn at one end and has a magnet mounted on its other end sothat the magnet moves adjacent a reed switch to cause it to close itscontacts when the end comes down. In one system for use with suchdetectors, a number of reed switches are connected to a plurality ofdata lines with each switch being connected to a unique combination ofthose lines. Logic units each comprising a number of relays eachconnected to one of the data lines is associated with each reed switch,with those relays connected to a line to which the reed switch is notconnected having a normally closed controlled switch and those relaysconnected to a line at the reed switch is connected having a normallyopen controlled switch so that a current path is produced through arecorder relay via all of the relay switches only when the associatedreed switch is closed in response to the detection of an ends downcondition.

Many other objects and purposes will become clear from the followingdetailed description of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows one embodiment of afluidic device which responds to a flow pressure signal by producing apneumatic pulse and which responds to the removal of that flow pressuresignal by producing a vacuum pulse and an electrical signal.

FIG. la shows an unconnected amplifier in the position where no vacuumsignal is being applied.

FIG. lb shows a further unconnected amplifier also in a position whereno vacuum signal is coupled to the input.

FIG. 2 shows a piston member for use in a switch such as shown in FIG.1.

FIG. 3 shows another embodiment of the pneumatic device for generating apneumatic and electrical pulse in response to a low pressure signal.

FIG. 4 shows another device for generating a pneumatic pulse in responseto a low pressure input signal.

FIG. 5 shows a piston and diaphragm arrangement providing better sealingand more friction free operation.

FIG. 6 shows another embodiment similar to that of FIG. 5.

FIG. 7 shows a piston press-fitted onto a piston member.

FIG. 8 shows a plurality of ends down detecting units mounted on aspinning frame and connected to auxiliary components.

FIG. 9 shows a cut-away view of one of the units of FIG. 8.

FIG. 10 shows a front view of one of the units of FIG. 8.

FIG. 11 shows a cut-away view of an amplifier and counter receiving apneumatic pulse.

FIG. 12 shows a cut-away view of the amplifier and counter of FIG. 11while not receiving a pulse.

FIG. 13 shows another amplifier and counter.

FIG. 14 shows yet another amplifier and counter.

FIG. 15 shows a cut-away view of another ends down detector wherein theyarn blocks a passageway when present.

FIG. 16 shows an end down detector wherein the absence of yarn causes amagnet to be moved adjacent and to close a reed switch.

FIG. 17 shows a top view of the detector of FIG. 16.

FIG. 18 shows a system for determining which reed switch ofa number ofreed switches has been closed in response to an ends down condition.

FIG. 19 shows a system for determining which of a number of pneumaticdetectors connected to a common manifold has produced a signal inresponse to the detection of an ends down condition.

FIG. 20 shows another system for determining which of a number ofpneumatic detectors connected to a common manifold has produced a signalin response to the detection on an ends down condition.

FIG. 21 shows a timing chart for the logic of FIG. 20.

FIG. 22 shows yet another system for determining which of a number ofpneumatic detectors connected to a common manifold has produced asignal.

FIG. 23 shows an ends down detector mounted on a spinning frame.

DETAILED DESCRIPTION OF THE DRAWINGS Reference is now made to FIG. 1which shows one embodiment of this invention which responds to a lowpressure input signal by producing a pneumatic pulse and responds to theremoval of that signal by producing a vacuum pulse and an electricalpulse which can then be passed to ancillary devices and used as desired.The simple unit 20, illustrated in FIG. 1, includes a housing 22 havinga bore 24 in it. An electrically conductive air supply tube 26, whichconnects to the input device which supplies the low pressure signal,runs through the center of bore 24 and extends through the otherwisesolid rear of housing 22. Tube 26 is open at both ends as shown.

An operating piston member 30, which can be seen best in FIG. 2, islikewise disposed in bore 24 and is free to slide along both tube 26 andbore 24 toward and away from spring 32. Two gripper springs 34 and 36are fixed permanently to the rear of piston member 30 and a bezel 38 ispress-fitted into bore 24 and shouldered against the outside and frontend of housing 22 as shown. Bezel 38 provides a stop for the pistonmember 30 against its shoulder 40.

At the rear of the bore 24, a movable electrical contact 42 capable ofmoving along tube 26 and a stationary electrical contact 44 fixed inplace are both provided for generating an electrical pulse when the lowpressure signal applied to tube 26 is removed as discussed in detailbelow. Spring 32 is fitted against the rear of bore 24 so as to urgepiston member 30 toward bezel 38 after it has compressed spring 32 inmoving rearward in response to a low pressure signal. A second spring 46is provided between contacts 44 and 42 and spring 46 continuously urgesmovable contact 42 rearwards, away from stationary contact 44.

When a low pressure pneumatic signal is applied to tube 26, for examplein response to the opening of a valve, the closing of a switch,operation of a proximity fluidic sensor or other similar device, thepressure resulting from the signal thus applied builds up between theinside face of the bezel 38 and the outside face of piston member 30.When the force urging piston member 30 rearward which results from thispressure buildup exceeds the small frictional force between the surfaceof piston member 30 and bore 24, piston member 30 moves rearward in bore24 toward spring 32, eventually compressing it until the force exertedby spring 32 on piston member 30 balances the force exerted by thepressure generated by the low pressure signal. Spring 32 is compressedsufiiciently so that the gripper springs 34 and 36 grip movableelectrical contact 42.

As the piston member 30 moves rearward in bore 24, output line 50 ismomentarily connected to tube 26 via groove 52 of piston member 30 whichis momentarily aligned with the open end 54 of output line 50. A bore56, which can also be seen in FIG. 2, connects groove 52 to tube 26.Thus, a single positive pneumatic pulse is produced for each rearwardmovement of piston 30 in response to a low pressure pneumatic signal andthis pulse can be transmitted to any appropriate device for recordingthe presence of the low pressure signal on tube 26 or employing thatpulse in any suitable fashion.

Further, as piston member 30 moves rearward toward spring 32, a slightpressure builds up at the rear of piston member 30 in the enclosedportion of bore 24. That pressure is communicated through output line 60to ball valve 62, causing ball member 64 to move away from its seat 63which seals line 66, compressing sprong 68 and thus pneumaticallyconnecting line 66 to line 60 and transmitting the relatively highpressure pneumatic pulse created by the rear movement of piston member30 to line 66. A conventional restrictor 67 is provided in line 66 tolimit the amplitude of the high pressure pulse transmitted.

The pressure signal communicated to line 66 causes pilot diaphragm 68 ina conventional amplifier valve 70 to move to the position shown, closingaperture 71. Pressure now builds up in region 72 behind spool diaphragm73 since region 72 is connected to source 74 via inlet 75. This pressurebuilds up causes diaphragm 73 to shift to the illustrated positiondisconnecting exhaust line 76 from line 77 and connecting line 77 toline 78 which is connected to source 74 so that air flows from source 74to line 77 and out outlet 79 as indicated by the arrows to a devicewhich then employs the amplified pneumatic signal as desired. Anunconnected amplifier 80 is also shown in FIG. la in the condition whereno signal is being applied and when ball 64 returns to close seat 63, byeither the forward movement of piston member 30 or the dissipation ofthe pressure behind member 30 via restrictor 67, diaphragms 68 and 73return to the positions illustrated in amplifier 80. Other devices canof course be connected to line 66 to use the signal generated by theopening of valve 62 in any suitable way.

Thus upon the application of a relatively low pressure signal to tube26, piston member 30 moves rearward compressing signal 32 at least untilgripper members 36 and 38 have gripped stationary contact 42 and pistonmember 30 remains in this position until the low pressure signal isremoved from line 26. When this occurs and the pressure on the outerface of the piston member 30 adjacent bezel 38 no longer exceeds theforce exerted by spring 32 urging piston member 30 toward bezel 38,piston member 30 moves toward bezel 38, dragging movable contact 42 heldby gripper springs 34 and 36 with it. When movable member 42 contactsstationary member 44, an electrical circuit is completed between contact81 on the exterior of unit 20 and ground via tube 26, which is connectedto ground as shown, stationary contact 44, movable contact 42 and line82. Contact 81 is preferably connected to a solenoid, transistor orother device for detecting and recording the pulse generated by theconnection of contact 81 to ground. After momentary electricalconnection, stationary contact 44 and movable contact 42 separate aspiston member 30 continues moving toward bezel 38 under the influence ofspring 32 and gripper members 34 and 36 release stationary contact 42which then moves rearwardly away from stationary contact 44 to itsillustrated position under the influence of spring 42. Thus, the removalof the low pressure signal from the tube 26 generates a detectableelectrical pulse which can be used in any way desired to record orrespond to the removal of pressure from tube 26.

Further, as piston member 30 moves back toward bezel 38, the reducedpressure in bore 24 behind member 30 creates a reduced pressure in line62 to which ball valve 83 corresponds as ball 84 moves away from valveseat 85 against spring 86 thus connecting line 90 to line 60. Theresulting reduction of pressure in line 90 causes pilot diaphragm 91 inamplifier 92 to shift upwards against spring 93 to the positionillustrated uncovering aperture 94. Aperture 94 now connects source 74to exhaust 95, relieving the pressure above spool diaphragm 96 whichmoves upward to the position illustrated connecting output 97 to source74 and thus generating a high pressure signal which can then be passedto other devices and employed as desired. An unconnected amplifier 98 isshown in FIG. lb in the position where no vacuum signal is coupled toits input.

FIG. 3 illustrates an embodiment of the invention similar to FIG. 1whereby a piston member 100 is mounted for free movement in a bore 102of a housing member 104 having an input tube 106 extending through itscenter as shown. As in the embodiment of FIG. 1, the application of alow pressure signal to tube 106 causes a pressure to build up betweenthe interior surface of bezel 106 and the exterior of piston member 100which causes piston member 100 to move toward spring 110 which thengenerates a force urging piston member 100 toward bezel 108. When groove112 of member 100 is aligned with output line 114, bore 116 in pistonmember 100 connects tube 106 to line 114 so that a low pressure pulse isgenerated on output line 114 which can be conveyed to any suitabledevice for recording or other use. However, in contrast to thearrangement illustrated in FIG. 1, in FIG. 3 instead of using grippers apermanent magnet 120 is permanently mounted on the rear of piston member100 as shown and interacts with a second permanent magnet 122 which ismovable within bore 102. Magnet 122 is connected as shown to members 126and 128 which are urged respectively away from bezel 108 by conventionalcompression springs 130 and 132 and members 126 and 128 terminate inmovable electrical contacts 134 and 136, respectively.

When the piston member is in the position shown before a low pressuresignal is applied to tube 106, lines 140 and 142 are electricallyconnected together by contacts 134 and 136. When piston member 100 movesrearward upon the application of a suitable low pressure signal to tube106, magnets and 122 move into close physical juxtaposition so that,when the low pressure is removed from tube 106, and piston member 100begins to move back toward bezel 108 under the influence of spring 110,magnet 120 pulls magnet 122 with it against the force generated bysprings 126 and 128, thus disconnecting line from line 142 andmomentarily thereafter connecting lines 148 and 150 via contacts 134 and136. Eventually, member 100 moves far enough toward bezel 108 so thatthe spring forces overcome the magnetic attraction of magnets 120 and122 or contacts 134 and 136 can move no further. At that time magnet 122is released and the electrical connection between lines 148 and 150 isbroken. Members 126 and 128 as well as contacts 134 and 136 now returnto their illustrated positions under the influence of springs 126 and128, electrically reconnecting lines 140 and 142 together. In thisfashion, an electrical signal is generated which indicates the removalof the low pressure source from tube 106 and this electrical signal canbe used in any fashion to respond to or record such removal.

FIG. 4 shows another embodiment of the invention somewhat similar tothat of FIGS. 1 and 3 whereby a piston member is provided with aboot-type diaphragm 162 which is stretch fitted over a small diameterprojection 163 of piston member 160 and is clamped at its outer diameterby a screw-in type bezel 164 by threads 166. Diaphragm 162 is thusclamped between shoulder 168 of housing member 170 and bezel shoulder172 thus providing much freer movement of piston 160 with less pressureloss.

As in the other embodiments, the application of a low pressure signal toline 175 causes piston member 160 to move rearward against the urging ofcompression spring 176. The pressure building up behind piston member160 within chamber 178 as the piston member 160 moves rearward causesball valve member 180 to be displaced against spring 182 and thusconnect line 184 to line 186 and generate a low pressure pneumatic pulsewhich can be conveyed to conventional devices to record or respond tothe application of a low pressure signal on line 184 as desired. Afterthe low pressure signal is removed from line 175 and piston member 160begins to move back toward bezel 164, the resulting reduced pressure inchamber 178 causes ball member 190 to be displaced upward against spring191 thus unsealing valve seat 192 and connecting output line 194 to line186 to produce a momentary pneumatic pulse upon the removal of the lowpressure source from line 175.

FIGS. 5 and 6 illustrate an arrangement which is similar to that of FIG.4 but which is provided with a diaphragm somewhat differently connectedto provide better sealing and less friction. In FIG. 5, a moldeddiaphragm 200 is fitted to housing 202 at its outer diameter in the samefashion as discussed above with regard to FIG. 4. Molded diaphragm 200fits over the front of piston 204 as shown and is preferably fastened toit by a metal orifice cut in flanged plug which provides a leak-proofseal. Piston 204 further has an integral small diameter extension 210which is fitted into bore 212 for the purpose of receiving a lowpressure signal from tube 214 which receives the low pressure signal inthe same way as described above with the other embodiment. Thus, arelatively high pressure signal results on output line 220 as piston 204moves away from bezel 222 in response to the application of a lowpressure signal to tube 214. Similarly when piston 204 moves backtowards bezel 222 under the urging of spring 210 in response to theremoval of the low pressure signal, a vacuum signal results in line 220.

In the embodiment of FIG. 5, diaphragm 200 is fitted to housing 202 inthe same manner as described above with regard to FIG. 4 and ispreferably fastened to piston member 204 by a flanged plug whichprovides a leak-proof seal. FIG. 6 shows piston 204 in its position whena low pressure signal is being applied to line 214.

FIG. 7 shows a cut-away view of a typical piston 252 such as shown inFIGS. 5 and 6 press-fitted onto a flanged head tube 254 which clamps aflexible diaphragm 256 between the flange and the flanged end of tube254. Such an arrangement provides a complete pulsing piston that willperform satisfactorily in the embodiments of FIGS. 5 and 6.

As pointed out briefly aboee, the unique device de scribed in FIGS. l-7is particularly useful in conjunction with fludic sensing devices wherelow pressure signals are frequently generated and it is necessary ordesirable to record or respond to the presence of these low pressuresignals. Further while the embodiments shown in FIGS. 1-7, as well asdevices of FIGS. 8-15, can be of course used in conjunction with otherdevices, they have particularly utility in the environment of a textilemill and more particularly for sensing and detecting an ends downcondition on a spinning frame. While the following description isdirected to the use of such devices in this particular environment, itwill of course be understood that the novel invention of thisapplication is not limited to that important application.

Reference is now made to FIGS. 8 and 9 which show respectively aplurality of pneumatic sensing devices of the type described above inFIGS. 1-7 mounted on a thread board for sensing an ends down conditionand a cut-away view of one such sensor. While only three sensors areshown attached to a conventional thread,

board 300 in FIG. 8, it will of course be understood that any number ofsuch sensors can be provided in any particular enivornment such as aspinning frame, each associated with a thread or yarn for detecting theend of that thread. As with existing sensor devices, each unit ispreferably attached by a hinge to the thread board as shown to permitindividual raising of each unit for maintenance and replacement asnecessary. Similarly, the thread board preferably fastens to lifter rodsso as to facilitate raising groups of sensors for the purpose ofdropping full bobbins and installing new ones.

A source of air under pressure is connected to each of the units 302,304 and 306 illustrated in FIG. 8 through a conventional pressureregulating valve 308 which produces a continuous low pressure signal inthe range of l to 5 psi which is preferably shown on gauge 310 asillustrated in FIG. 8. A suppy manifold line 312 transmits this pressuresignal to the individual supply lines 314, 316 and 320 whichindividually connect to the units 302, 304 and 306, respectively.

Reference is now made to FIG. 9 which shows a detailed cut-away view ofsensor 302 from which the operation of that sensor and the other sensorsshould be readily apparent. The pressure signal from the valve 308 isconveyed into unit 302 via supply line 314 and the air enters areceiving chamber 322 in unit 302 via a supply port 323 and a flowrestrictor 324 which precludes a substantial pressure drop in line 312which might keep other units from operating properly. Even with 119units venting, if the 120th needs to operate, the system shown willsupply sufficient pressure for it to do so. Flow restrictor 324 ispreferably a calibrated orifice having a bore carefully chosen torestrict the fluid flow to whatever extent is necessary.

As can be seen in FIG. 9, chamber 322 is connected to the atmosphere viapassages 325 and 326. However, a sensor yoke member 328 is disposed inthe opening of passage 326 into the atmosphere. Sensor yoke 328 isprovided with a rearwardly extending hollow valve stem 330 which blocksthe connection between passages 326 and 324 when the yoke 328 is forcedbackwards from its illustrated position into unit 302 and vents chamber322 to the atmosphere via passage 331 when in its illustrated position.As can be seen in FIG. 8 in connection with the unit 304, a pigtailmember 332 is disposed about the yoke 328 and is preferably providedwith a slubbing slot 334. The yarn end does not thread through slubbingslot 334, but rather the yarn is threaded behind member 332 and in backof holder 340. When any unusually heavy slub in the yarn passes frombetween the front rolls, the yarn ends breaks due to the centrifugalforce of the end being spun and is thrown around pigtail guides 332,thereby catching the slub in slot 334, thus breaking the slub out of theyarn end. When yarn is so threaded, pigtail member 332 is positioned asshown in FIG. 10 so as to force the stem 330 of yoke 328 into unit 302,and to thus normally block the connection between passages 325 and 326.Pigtail member 332 is shown removed from unit 304 for greater clarity inillustration. As can be best seen in connection with unit 302 in FIG.10, a thread holder 340 is preferably provided on unit 304, as well asthe other units, and is held in place by a set screw 342. The purpose ofthe thread holder 340 is to keep the yarn end from being thrown out whendoffing, starting up or when a heavy slub comes through.

When yarn is present and accordingly yoke stem 330 is forced inward toblock the connection between passages 325 and 326, pressure builds up inchamber 322 and is transmitted through passage 344 into chamber 346.This pressure is further communicated through passage 348 in fixedmember 345 into passage 350 which runs through piston member 360 whichis free to move within bore 370. Passage 350 connects to passage 356which in turn terminates in the region between the front of piston 360and bezel 362. This pressure forces piston 360 which is, as are thepistons in the other embodiment, freely movable within bore 370rearwards against and compressing sprnng 372 as shown.

Thus, when stem 330 blocks the outlet of passage 325, as in the casewhen the yarn presence is sensed, piston member 360 is in itsillustrated rear position with the front thereof withdrawn from initmatecontact with transparent bezel 362. Preferably the front portion ofpiston member 360 which contacts bezel 362 is colored red or some othersuitable color so that it is readily observable to denote a flagcondition after it moves forward into contact with bezel 362 under theurging of spring 372 and in response to the removal of pressure fromchamber 346 which takes place in response to the venting of chamber 322to the atmosphere via passages 325 and 326.

Thus, when an ends down condition occurs, piston member 360 movesforward from its illustrated position until its front potion contactsbezel 362 and the red or other color of that portion is readily visiblethrough transparent bezel 362. Similarly, when a new yarn has beenplaced through the slot of the associated pigtail, the piston memberthen returns to its illustrated position. As piston member 360 movesrearward from its forward position against spring 372, passage 380 ismomentarily connected to passage 350 via an opening 382 in piston 360 sothat a low pressure pulse is thus transmitted to chamber 390 and outindividual line 392 to a fluidic amplifier 394 and a suitable andconventional pneumatic counter 396. A ball 392 is disposed in chamber390 so that when unit 302 is lifted for maintenance or for any otherreason, ball 395 rolls to a position blocking port 397 which connectschamber 390 to line 392 and thus preventing production of a false signalduring the time unit 302 is in the lifted position. The low pressurepulse recorded on counter 396 thus indicates a return to normalcondition of one of the sensor units 302, 304 or 306 which are allsimilarly connected to amplifier 394. Amplifier 394 is supplied withpressure from a suitable source via valve and gauge 399 and line 398.

While counter 396 records the total number of ends down on all unitstogether, recorders such as counter, relays, tap puncher or otherencoders can be associated, if desired, with each unit to record thenumber of low pressure pneumatic pulses produced by that unit and hencethe number of ends down conditions detected by that unit. To illustrateone such arrangement conventional recorder 400 in FIG. 8 is shownconnected to line 402 for receiving and detecting each low pressurepulse produced by unit 304.

FIGS. 11 and 12 show respectively a cut-away view of amplifier 394 andcounter 396 in position receiving a pneumatic low pressure pulse fromone of the units such as unit 302 and in position not receiving a pulse.Amplifier 394 operates similarly to amplifier 70 of FIG. 1 and referenceshould be made to the discussion of amplifier 70 above for a detaileddescription of the operation of this type of amplifier.

Briefly, the arrival of the pneumatic pulse in chamber 404 causes pilotdiaphragm 406 to shift from the position illustrated in FIG. 12 to theposition of FIG. 11, blocking aperture 407. Pressure now builds up inchamber 408 which is connected to line 398 via passage 410 through themiddle of spool diaphragm 412. Line 398 connects to a pressure sourcevia gauge and valve 399 as shown in FIG. 8. This pressure in chamber 408forces spool diaphragm 412 downward connecting passage 414 to line 398.

Passage 414 is connected to chamber 416 which is located behind piston418 in counter 396. A flexible diaphragm 420 seals chamber 416 andpermits movement of piston 418. Thus, as spool diaphragm 412 movesdownward and connects passage 414 to line 398, pressure builds up inchamber 416 forcing piston 418 to move toward ratchet wheel 424 and tocompress spring 426. When the low pressure pneumatic signal ends, pilotdiaphragm 407 and spool diaphragm 412 shift back to the positionsillustrated in FIG. 12, connecting chamber 416 to the atmosphere viapassage 430. Spring 426 now forces piston 418 back to the position shownin FIG. 12. At the same time, hook 432, which has engaged one of theteeth on ratchet wheel 424, rotates wheel 424 through an angle whichthen represents a count of one ends down condition.

FIGS. 13 and 14 depict two other suitable pneumatic amplifiers andcounters. While these arrangements are discussed specifically inreference to the individual recorder 400, it will, of course, beapparent that they can also be employed in place of amplifier 394 andcounter 396 if desired. In FIG. 13, the pneumatic pulse received on line402 causes pressure to build up in chamber 440 behind flexiblediaphragms 442 which responds by bowing toward electrical contacts 444and 446. A quantity of mercury which is not normally sufficient toconnect together contacts 444 and 446 is stored in the region behinddiaphragm 442 and, as diaphragm 442 bows, this mercury is forced intothe space adjacent contacts 444 and 446 to electrically connect thesecontacts together, and permit current to flow through conventionalcounter 450 which thus records the detection of an ends down condition.When the pulse is removed, vent 451 bleeds the pulse pressure to theatmosphere, diaphragm 442 moves back to its initial position and theconnection between contacts 444 and 446 is broken.

In FIG. 14, the pneumatic pulse forces piston 452 to move towardcontacts 454 and 456 against the urging of spring 458 until bar 460electrically connects contacts 454 and 456 so current flows toconventional electrical counter 460 to record the detected ends downcondition. When the pneumatic pulse is removed spring 458 forces piston452 back to its illustrated position, breaking the connection betweencontacts 454 and 456.

Reference is now made to FIG. 15 which shows a sensing unit 500 similarto unit 302 illustrated in FIG. 9. However, in contrast to theembodiment of FIG. 9, unit 500 employs no sensor yoke or valve stem. Theyarn itself serves to block a passageway connecting a receiving chamberto the front of a piston so that when the yarn end comes down thepressure in the receiving chamber is communicated through a hollowpassageway in the piston to the region between the inside of the bezeland the front of the piston so that the piston moves rearward toelectrically connect together two contacts and indicate an ends downcondition. Thus, the rear position of the piston member away from thebezel indicates the presence of an ends down condition, while itsforward position pressed against the inside face of the bezel denotes anormal condition.

' As in the embodiment of FIGS. 8 and 9, a suitable source of pressureis connected to a receiving chamber 502 in unit 500 via a suitable valve(not shown), an inlet aperture 504 and a restriction valve 506. Chamber502 is connected to a second chamber 510 via line 512, as shown, andwhen a yarn such as yarn 514 is disposed in chamber 510, as shown, yarn514 blocks communication between passages 512 and 516 so that most ofthe air vents to the atmosphere via exhaust 520. However, when the yarnend comes down, a substantial portion of the air moving from the passage512 into chamber 510 passes into passage 516 which empties into chamber524. Chamber 524 communitcates via passage 532, through the middle ofpiston member 530, with the interior region 526 between the inside faceof the bezel 528 and the front of piston member 530. The resultingpressure build up in region 526 forces piston 530 backward, compressingspring 534 within chamber 524. Piston 530 is illustrated about half waybetween its forward and rear position.

Eventually the pressure in chamber 526 forces piston 530 back to thepoint where ring 538 contacts electrical connections 540 and 542. Inthis position, piston 530 can move no further to the rear, andelectrical connections 540 and 542 remain connected together by ring538, thus completing a current path through relay 544. Relay 544responds to the passage of current through it by shifting solenoid lever546 so as to cause member 548 to pivot about a pin 550 from the positionroughly shown in dashed lines to the position shown in solid. Member 548includes a hook 552 on its lower portion, and hook 552 engages a toothon ratchet 554 so that its rotational movement of member 548 about pin550 rotates ratchet wheel 550 to the position illustrated.

Ratchet wheel 554 is mounted for rotation with a second wheel 558, forexample, on the same shaft, so that the rotation of ratchet wheel 554rotates wheel 558 which is provided with a number of cam members. Therotation of wheel 558 forces cam follower member 560 to rotate aboutpivot point 562 and force contacts 564 and 566 into momentary connectionthus generating a pulse of current which is applied to conventionalelectrical counter of 568 to record the detected ends down condition.

When the yarn is replaced in chamber 510, the pneumatic connectionbetween passages 512 and 516 is interrupted with the result that thepressure built up between the inside face of bezel 528 and the frontportion of piston 530 is dissipated so that piston member 530 returns toits former position under the urging of spring 534, in preparation forthe next detection of an ends down condition.

FIGS. 16 and 17 illustrate another simple ends down detector. As withthe embodiment of FIG. 8, a number of such detectors will normally bepivotably mounted on a thread board, but, for clarity, only one detector470 is shown in FIGS. 16 and 17. Detector 470, however, in contrast tothe other embodiments discussed above, does not generate a pneumaticpulse in response to an ends down detection, but instead generates anelectrical one. In the embodiment of FIGS. 16 and 17, this isaccomplished by providing a magnet on one end of a pigtail guide so thatwhen the end comes down the magnet moves adjacent a reed or similarswitch to generate an electrical signal.

Mounting block 472 is grooved as shown to accomodate a stationaryconventional reed or similar switch 474 and rotatable pigtail guide andslubber 476. Guide 476 is attached to a rotatable member 478 which islodged in groove 480 as shown so that guide 476 is pivotable about itspoint of attachment to member 478. Further, magnet 482 is mounted on theshort end of guide 476 so that when no yarn is in eye 484, guide 476shifts to the position shown in dashed lines in FIG. 16 with magnet 482adjacent reed switch 474. When magnet 482 is so positioned, the contactsin switch 474 are closed and this condition can be easily detected byapplying an appropriate electrical signal to lines 490 and 492 whicheach connect to one of the contacts. Similarly, when yarn is in eye 484,guide 476 tips to the position shown in solid in FIG. 16 with magnet 482held far enough away from switch 474 so that the contacts of that switchare open. Thus a readily detectable electrical signal results from eachends down condition of the yarn or thread which passes through eye 484.

Reference is now made to FIG. 18 which shows a simple logic arrangementfor detecting and recording the closing of reed switches such as shownin the embodiment of FIGS. 16 and 17. As discussed above, such units arenormally grouped with a large number of other units and, accordingly, itis desirable to be able to monitor the open or closed condition of alarge number of such reed switches with a minimum number of lines andelectrical equipment. While in FIG. 18 only reed switches 570, 572, 574and 576 are illustrated, it will be understood that the logic circuitshown in FIG. 18 will normally be used with a large number of suchswitches. The eight-line detection system shown in FIG. 18 will, ofcourse, be capable of handling 255 switches and the system can easily beexpanded by simply adding additional lines.

In the embodiment of FIG. 18, each of the reed switches in the system isassigned a unique binary number and is connected to a unique combinationof the eight output lines 578, 580, 582, 584, 586, 588, 590 and 592which represents that binary number. A number of logic units equal tothe number of reed switches served by the system are connected to lines580, 582, 584, 586, 588, 590 and 592 for recording the detectedconditions of each of the various reed switches. Four units 594, 596,598 and 600, associated respectively with switches 570, 572, 574 and576, are shown in FIG. 18.

Each of these logic units responds only to the closing of its associatedreed switch which connects a source of voltage of its unique combinationof lines. For example, a relay connected to each of the lines, as shown.Relays associated with lines to which the associated switch is connectedcontrol normally open switches while relays connected to lines which theassociated switch is not connected control normally closed switches, asshown. Thus, a recognition signal is produced on line 602 and passedthrough a coil of relay 604 only when line 578 is connected to thesource of voltage and none of the other lines are so connected, becauseonly under these conditions are all of the switches associated with therelays closed. The passage of current through relay coil 604 causes arecorder, such as ratchet wheel 606, to record the detection of an endsdown condition by switch 570. Similarly, units 596, 598 and 600 haverelays similarly connected to all of the lines which have normally openand normally closed switches so that a signal is recorded whenever theunique combination of lines indentifying that switch and thatcombination only is connected to the voltage source by the associatedreed switch. The detection of an ends down does not usually occur oftenenough to cause substantial confusion by the closing of differentswitches at the same time.

FIG. 19 shows a detection system suitable for determining which of anumber of individual units connected to a common supply manifold havedetected an ends down condition and produced a pneumatic pulse such asin the embodiments of the FIGS. 8 and 9. Five units 610, 612, 614, 616,and 618 are shown connected to a supply manifold 620. These units arepreferably the same as shown, for example, in FIG. 9 so that uponoccurence of an ends down condition, a pneumatic signal is conveyed tomanifold 620 and travels in opposite directions both toward pneumaticdevices 622 and toward pneumatic device 624. Since pneumatic device 622is closer to each of the units 610, 612, 614, 616 and 618 than pneumaticdevice 624, the pneumatic pulse will arrive there first. The arrivingpulse causes a flexible diaphragm 626 in device 622 to move a contact628 into connection with two contacts 630 and 632 thus completing acurrent path through a conventional electrical clutch 634 which engagesa motor 638 to a contact wheel 640 for a single turn of wheel 640. Wheel640 is provided with a contact 642 which extends beyond the periphery ofwheel 640 and connects in turn to a number of output lines of which fourare illustrated in FIG. 19, each representing one detection unit onmanifold 620. It will, of course, be understood that one such line willbe provided for each unit which is in the system.

Extending contact 642 is electrically connected to contact 644 which isclosed by the movement of flexible diaphragm 648 of pneumatic device 624upon arrival of the pneumatic pulse in manifold 620 at device 624. Thearriving pulse thus closes the connection between electrical contact 644and 650 and completes a momentary current path through the recorder 660,662, 664 or 666 which is associated with the unit which produced thepneumatic pulse. The distances which a pneumatic pulse travels from thelocation where each of the various units is connected to supply manifold620 to devices 622 and 624 are different and accordingly the angularposition of wheel 640 at the time that contacts 644 and 650 areconnected together is different for each unit.

Reference is now made to FIG. 20 which shows another arrangement similarto that of FIG. 19 for recording which of a'number of units connected toa common supply manifold has produced a pneumatic pulse indicating adetected ends down condition at that particular unit. As in theembodiment of FIG. 19, a plurality of detector units are connected incommon to a supply manifold 680 which terminates at one end in aconventional pneumatic amplifier 682 and at the other end in anotherconventional amplifier 684. Amplifiers 682 and 684 are connected to asource of pressure 686 by a suitable line as shown, and these amplifiersmay be of the type shown in FIGS. 10 and 11. Thus, a pulse .produced byone of the units, for example, unit 690, is transmitted in bothdirections in supply manifold 680 and arrives first at amplifier 682,which responds by producing an output on line 692 which is conveyed asshown to the logic generally indicated as 696, and thereafter arrives atamplifier 684, which similarly produces an output on line 790 which isalso conveyed to logic 696.

The pneumatic signal produced by amplifier 682 is first conveyed to theleft-hand input of pneumatic NOR gate 700 which is a type of logicdevice which is well known. Briefly, the application of a pneumaticpulse to the left-hand input 702 of NOR gate 700, while a source ofpressure is being applied to main input 704, causes the air enteringgate 700 through input 704 to be deflected out the output 706.Similarly, signal applied to right-hand input 708, while air is beingapplied to main input 704, cuts off the flow of air from output 706remains cut off until that other signal is applied to left-hand input702. A signal applied to input 702 when output 706 is open has no effectand similarly a signal applied to right-hand input 708 when output 706is closed has no effect.

Thus, the reception of the pneumatic pulse by amplifier 682 and theproduction thereafter of an amplified pneumatic signal on line 692results in the application to left-hand input 702 of a pneumatic signalwhich causes NOR gate 700 to generate a pneumatic signal at output 706,since main input 704 is connected to source 687 via line 707. The samesignal which is applied to left-hand input 702 also is applied toright-hand input 708 via restrictor 710 and pneumatic capacitor 712 sothat, after a short period has elapsed following the application of asignal to left-hand input 702, a signal is applied to right-hand input708 which causes the signal produced at output 706 to end and the NORgate 700 to remain shut off until the signal on line 692 is removed anda new signal applied to left-hand input 702. Referring to FIG. 21 of thedrawings which depicts the operation of the various elements in logic696, the depicted signal from amplifier 682 causes NOR gate 700 to shiftfrom its 1 condition in which there is no signal at output 706 to its 0condition in which a signal is produced at output 706. After a shorttime, as determined by the capacitance of the pneumatic capacitor 712,has elaspsed NOR gate 700 reverts to its 1 condition and remains in thatcondition for the remainder of the cycle.

The pneumatic signal produced at output 706 is applied to right-handinput 714 of oscillator 720, and the output of amplifier 602 on line 692is similarly applied to main input 716 of oscillator 720. Oscillator 720operates similarly to NOR gate 700 in that the application of apneumatic pulse to its right-hand input 714, when a signal is beingapplied to main input 716, causes a signal to be produced at itsleft-hand or 1 output 720, and no signal on right-hand output 726, whilethe application of a pneumatic signal to be produced on right-handoutput 726 and no signal on right-hand output 720. The application of apneumatic signal to right-hand input 714 while a signal is beingproduced at left-hand output 720 or the application of a signal toleft-hand input 724 while a signal is being produced at right-handoutput 726 has no effect. Outputs 720 and 726 are exclusive, i.e. eitherone or the other, but not both, will at all times have an output signalwhen a suitable signal is being applied to main input 716.

Thus, the receipt of a pneumatic signal on input 714 causes oscillator720 to shift, as shown in FIG. 21, from its 0 to its 1 condition so thata pneumatic signal is produced at left-hand output 720, but no signal isproduced at right-hand output 726. As shown, the signal produced atleft-hand output 7 20 is applied to left-hand input 724 via restrictor730 and capacitor 736 so that, after a given time has passed asdetermined by the capacitance of pneumatic capacitor 736, the signalthus applied to input 724 causes oscillator 720 to shift its conditionso that a signal is produced at right-hand output 726 instead ofleft-hand output 720. The production of a signal at right-hand output726 causes a signal to be applied to right-hand input 714 via restrictor740 and pneumatic capacitor 742 so that after a given period of time, asdetermined by the capacitance of the

1. An apparatus for detecting and rEsponding to the absence of a strandof material or the like comprising: a housing member having a bore, apiston member movable in said bore, means for receiving a continuouspneumatic signal, means for detecting the absence of said strand, fortransmitting said pneumatic signal to an enclosed region at the front ofsaid piston member so that said piston member moves in said bore from afirst to a second position when the presence of said strand is detectedand for preventing the transmission of said signal to said enclosedregion when the absence of said strand is detected, means for urgingsaid piston member from said second to said first position so that saidpiston member returns to said first position whenever the transmissionof a signal being transmitted is prevented, and a transparent bezelmember mounted on the end of said bore so that the front of said pistonmember is visible through said bezel member when said piston member isin said first position.
 2. An apparatus as in claim 1 wherein saidreceiving means includes a chamber in said housing member, wherein saiddetecting, transmitting and preventing means includes a passageway insaid housing member connecting said chamber to the atmosphere, a valvemember having a valve stem for blocking said passageway when said valvemember is in a first position and unblocking said passageway when saidvalve member is in a second position, means engaging said strand andassociated with said valve member for causing said valve member toassume said first position when no strand is engaged and said secondposition when a strand is engaged, and a second passageway is saidhousing member connecting said chamber to a region at the rear of saidpiston member and wherein said piston member has a passageway through itconnecting said region at its rear to said enclosed region.
 3. Anapparatus as in claim 2 wherein said receiving means further includesmeans for restricting flow into said chamber.
 4. Apparatus as in claim 1wherein said urging means includes a spring.
 5. Apparatus as in claim 1wherein the front of said piston member is colored red.
 6. Apparatus asin claim 1 wherein said receiving means includes a first chamber in saidhousing member, wherein said detecting, transmitting and preventingmeans includes a first passageway in said housing member connecting saidchamber to a first chamber open to the atmosphere and a secondpassageway connecting said second chamber to a region at the rear ofsaid piston member so that said pneumatic signal is transmitted to saidrear region when said strand is not disposed in said second chamber andis not transmitted to said rear region when said strand is disposed insaid second chamber and wherein said piston member has a passagewaythrough it connecting said rear region to said enclosed region. 7.Apparatus as in claim 6 further including first contact means mounted onsaid piston member and second contact means disposed in said bore sothat an electrical signal is produced by the electrical connection ofsaid first and second contacts when said piston member is in said secondposition.
 8. Apparatus as in claim 7 further including means responsiveto the initial production of said electrical signal for recording thedetection of the absence of said strand.
 9. An apparatus for detectingand responding to the absence of a strand of material or the likecomprising: a housing member having a bore, a piston member movable insaid bore, means for receiving a continuous pneumatic signal, means fordetecting the absence of said strand, for transmitting said pneumaticsignal to an enclosed region at the front of said piston member so thatsaid piston member moves in said bore from a first to a second positionwhen the presence of said strand is detected and for preventing thetransmission of said signal to said enclosed region when the absence ofsaid strand is detected, means for urging said piston membEr from saidsecond to said first position so that said piston member returns to saidfirst position whenever the transmission of a signal being transmittedis prevented, and means for producing a pneumatic pulse when said pistonmember moves from said second to said first position.
 10. Apparatus asin claim 9 wherein said piston member has a passage through it fortransmitting said pneumatic signal and wherein said producing meansincludes a second passage from said passage through said member to anopening in said piston member adjacent said bore and a third passage insaid housing member opening in said bore so that as said piston membermoves from said first to said second position said opening in saidpiston member is momentarily aligned with said opening of said housingmember in said bore to communicate said pneumatic signal to said thirdpassage.
 11. A system determining which of a number of pneumatic devicesconnected to a common manifold has produced a pneumatic signalcomprising: a number of said pneumatic devices each including: a housingmember having a bore, a piston member movable in said bore, means forreceiving a continuous pneumatic signal, means for detecting the absenceof a strand of material, for transmitting said pneumatic signal to anenclosed region at the front of said piston member so that said pistonmember moves in said bore from a first to a second position when thepresence of a strand is detected and for preventing the transmission ofsaid signal to said enclosed region when the absence of said strand isdetected, and means for urging said piston member from said second tosaid first position so that said piston member returns to said firstposition whenever the transmision of a signal being transmitted isprevented; a manifold connected to each of said devices so that eachsaid signal produced is transmitted from the location of the producingdevice both directions in said manifold, a first signal detecting deviceconnected to one end of said manifold for producing a first signal uponarrival of said pneumatic signal at said first device, a second signaldetecting device connected to the other end of said manifold forproducing a second signal upon arrival of said pneumatic signal at saidsecond device, and means for determining the time interval between theproduction of said first signal and the production of said second signaland accordingly which of said pneumatic devices produced said pneumaticsignal.
 12. A system for determining which of a number of reed switcheseach connected to a unique combination of data lines has changed itsposition comprising: recorder means associated with each said dataswitch, a number of relays associated with each said recorder means andeach having a controlled normally open or normally closed switch, eachrelay being connected to one of said data lines so that when said dataswitch changes its position all of said controlled switches will beclosed, means for connecting said recorder means to a source ofelectrical energy via each of said controlled switches so that saidrecorder means records a signal when said switch changes position, and apivotable member associated with each reed switch having a magnetmounted on one end and engaging a strand of material on the other end sothat when said strand is absent said magnet moves adjacent said reedswitch to cause it to close and when said strand is present said magnetmoves away from said reed switch so that its contacts open.